Limited travel carburetor metering rod



R. E. KALERT, JR, ET AL 3,350,074

LIMITED TRAVEL CARBURETOR METERING ROD Oct. 31, 1967 2 Sheets-Sheet 1Filed NOV. 8, 1965 FIG.

INVENTORS F I G 2 RALPH E. KALERT. JR. BYDONALD A. REISE ATTORNEY Oct.31, 1967 -r, JR ET AL 3,350,074

LIMITED TRAVEL CARBURETOR METERING ROD Filed Nov. 8, 1965 2 Sheets-Sheet2 g F I 3. 3. a7 w) 2 4 s5 INVENTORS "1m 82 RALPH E. KALERT,JR.

DONALD A. REISE BY 52 75 ATTO R NEY United States Patent Filed Nov. 8,1965, Ser. No. 506,670 4 Claims. (Cl. 261-51) This invention relates toa carburetor. It relates in particular to a carburetor utilizing acontrolled metering rod for more accurately regulating flow of fuel tothe carburetor mixing conduit.

In carburetors of the type presently contemplated, the flow of fuelpassing from the carburetor fuel bowl to the mixing conduit is regulatedto some extent by a metering rod positioned in an orifice connecting thesource of fuel with the mixing conduit. The primary purpose of ametering rod is to afford the carburetor a higher degree of efiiciencyand economy of function under all engine operating conditions.

This is achieved by regulating the position of the metering rod in theorifice to alter the flow of fuel passing into the carburetor dischargenozzle as the demand for fuel is varied by the engine. One suchregulating means includes a mechanical linkage connected directly to thecarburetor throttle and operable to alter the position of the meteringrod directly as the throttle is adjusted. Another means includes apneumatic or air motor arrangement connected to a source of vacuum suchas the engine inlet manifold, whereby variations in manifold vacuum arereflected in a comparable adjustment in the metering rod position.

It has been found that while the fuel metering rods above described arebeneficial in many respects to carburetor operation, under somecircumstances it is desirable that closer control be exercised toregulate fuel flow and consequently improve engine combustion. Further,where the air motor type arrangement is utilized, the reaction timelapse between the need for a richer air-fuel mixture, and the deliveryof sufiicient fuel to provide such a mixture is often excessive. Thisfollows since the usual air motor arrangement is designed to respondproportionately to the degree of manifold vacuum.

It has been found that under certain engine speeds and loads, anexcessive fuel delivery to the discharge nozzle results in an over-richair fuel mixture and the creation of large amounts of unburnedhydrocarbons which are discharged to the atmosphere with engine exhaustfumes. Engine operation under such circumstances is not onlyuneconomical, it also tends to aggravate a frequently present problem ofair pollution due to the emission of unburned hydrocarbons and otherundesirable matter into the atmosphere.

It is therefore an object of the invention to provide an improvedcarburetor having fuel metering means adapted to provide a moreefiicient and economical air fuel mixture to the engine. It is a furtherobject to provide an automatic control for metering fuel in a carburetorto avoid formation of over-rich air fuel mixtures. Another object is toprovide an automatic elongated fuel metering valve and actuatingmechanism therefor, automatically adjustable in response to both enginecondition and throttle position.

The foregoing objects together with others not specifically enumeratedwill be clear to those skilled in the art from the followingdescription.

The invention as herein disclosed is directed to a wellknown carburetorconstruction utilizing a fuel metering rod cooperative with an orificeformed in the base of the fuel well, the latter which forms a portion ofthe carburetor body. The well portion of the body is disposed within thecarburetor fuel bowl. The metering rod is arranged such that the taperedor metering end is operatively positioned within the fuel metering jet.

The upper end of the metering rod is retained in an air motor or similaractuating assembly responsive to both engine manifold vacuum and to theposition of the throttle. Thus, the metering rod is connected to adisplaceable diaphragm in the air motor which adjusts automatically inresponse to variations in engine manifold vacuum, which in turn normallycorresponds to engine load. The rod is controlled to avoid the normalreaction of the air motor to over-adjust at low engine speeds or rapiddeceleration, which would provide an over-rich air fuel mixture to theengine. It is further regulated to assure an adequately rich fuelmixture for automatically maintaining engine speed under road loadconditions which would cause a decrease in intake manifold vacuum.

In the figures; FIGURE 1 is a plan view of a car-buretor embodying thenovel features of the invention; FIGURE 2 is a substantiallylongitudinal cross-sectional view of the carburetor shown in FIGURE 1illustrated on an engine manifold; FIGURE 3 is a segmentary view on anenlarged scale of a portion of the carburetor shown in FIGURE 2; FIGURE4 is a segmentary view of a portion of the carburetor shown in FIGURE 2;and, FIGURES 5, 6, and 7 are segmentary views of the device shown inFIGURE 3 illustrating the apparatus in various stages of operation.

The invention is presently illustrated as incorporated into the body ofa single barrel carburetor similar to that shown in US. Patent3,189,333. It is understood however, that the following description ofthe fuel metering device is for the purpose of illustrating a particularstructure which may be applied equally as well to other forms ofcarburetors such as multi-barrel and the like.

Referring to FIGURE 1, the carburetor shown is similar in many respectsto that illustrated in US. Patent 3,189,333 and consists essentially ofa casting 10, Which is formed with a fuel and air mixture conduit 12,and a fuel =bowl cover portion 14 from which depends an accelcratingpump cylinder 16, an accelerating fuel passage 18, and a fuel wellstructure 20. Mixture conduit 12 is connected by a flange 13 to intakemanifold M of an internal combustion engine E. In the lower part of theconduit 12 there is rotatably mounted a throttle valve 22 fixed to athrottle shaft 24 journalled in appropriately aligned apertures in bodycasting 10. In the upper portion of the fuel air mixture conduit 12there is similarly mounted for rotational movement an unbalanced chokevalve 26 fixed to a choke valve shaft 28, which is also journalled inaligned apertures through the body casting 10.

The top of mixture conduit 12 is connected to an air filter 29,partially shown in cross-section in FIGURE 2. Between the upper andlower portions of the mixture conduit 12 is formed a venturi or air flowrestricting surface portion 30. A small booster venturi 32 is formedintegrally with body casting 10 and has an inner venturi surface 34coaxially aligned with the mixture conduit 12 and the primary venturisurface 30.

A fuel bowl 36 is fixed beneath fuel bowl cover 14 and is held with itsrim against a gasket 38 fitted between the rim of the fuel bowl 36 andmatching portions of the fuel bowl cover 14. A float structure 40 ispivotally mounted from pin 42 journalled in a depending portion of fuelbowl cover 14. A lever arm of float lever 43 fixed to float 40 abuts thelower end of a needle valve 44 having an upper tapered end extendinginto a valve seat 46 of the inlet 47 to the fuel bowl 36.

Normally, fuel is forced under pressure by pump 50 from the fuel tank52, through fuel line 48 and to carburetor inlet 47. When fuel level inbowl 36 is low, float 40 drops commensurably and lever arm 43 permitsvalve 44 to be displaced to an open position under fuel pressure. Fuelthen flows into bowl 36 until reaching a predetermined level. The needlevalve 44 is closed by the upward urging of fioat lever 43 as the fuellevel rises.

Referring to FIGURE 3, the lower end of fuel well 20 is closed by athreaded fitting 56 having a central orifice 69 which is formed toprovide a metering jet for the flow of fuel from the fuel bowl 36 tomixture conduit 12. A screw driver slot 57 is provided in the bottom offitting 56 to permit its removal. The upper end of fuel well 20intersects fuel passage 58 directed downwardly into secondary venturi32. A nozzle fitting 60 is held in the end of passage 58, one end of thefitting 68 extending into the secondary venturi 34. A fuel emission tube62 is fitted and supported within well 20.

A metering rod 66 is suspended within fuel well 20, having a meteringend 68 formed with varying diameters. The formed end 68 is positionedwithin the main fuel jet orifice 69 for operation in response to enginerequirements. Flow of fuel through main orifice 69 is controlled bymetering rod 66 and in accordance with that portion of the formed end 68which is positioned within opening 56.

The metering rod is accurately formed at the lower end thereof andengages the fuel orifice to permit maximum fuel efficiency. Inparticular, with the engine running at idle, the lower end 68 ofmetering rod 66 fits closely with the adjoining walls of orifice 69thereby defining a minimum annulus defining a sufficiently large fuelpassage to sustain the engine at idle. This will permit satisfactoryengine operation without over-enrichment of the fuel mixture, acondition that promotes excessive production of unburned hydrocarbons.

Referring to FIGURES 3 to 7, fuel well 20 includes a relatively narrowelongated channel formed substantially uprightly in the carburetor walland opening at the upper end into an enlarged bore 48 along an outwardlytapered surface 49. A peripheral shoulder 51 formed on tapered surface49 provides a rigid annular seat for flexible dia phragm 52 which isdisplaceable to inner and outer positions. Metering rod 66 includes anelongated central shank having a tapered portion 68 at one end thereofand an engaging head 53 at the other. Said engaging head 53 includes aperipheral shoulder 54 adjacent to a hub 59. Head 53 terminates at itsupper end in an enlarged annular projection 61 having opposed conicalseating surfaces 63 and 64 at the ends thereof, seating surface 64 beingconnected to hub 59 along a peripheral slide surface '67.

Metering rod 66 is connected at the head end 53 to a coupling 71 havinga washer 72 at the upper end and a shoulder 73 spaced from the washer. Abifurcated oscillating end 74 of the throttle lever 76 is urged by aspring 77 into engagement with upper washer 72, thereby providing aresilient yieldable connection between coupling 71 and the throttlelever 76, permitting a degree of throttle over-travel as lever 76 isactuated. Lever 76 is pivotally mounted to the carburetor body andconnected to the throttle shaft or to a suitable linkage associated withthe throttle shaft and with the accelerating pedal.

Metering rod 66 and coupling 71 are carried in an assembly including theflexible diaphragm 52 formed of rubber, fabric or the like supportedagainst shoulder 49 and held centrally by hub 59 and a cup member 78being urged against the diaphragm 52 by a spring 79. The peripheral edgeof diaphragm 52 is carried on annular shoulder 49 and maintained inplace by the upturned lip 81 of the spring retainer 82 which surrounds aportion of coupling 71 and includes one or more peripheral openings 83.

A thin walled guide member 84 carried in enlarged bore 48, includes aperipheral rim 86 positioning said member, and a cap 87 urging said rim86 into engagement with the walls of bore 48, holding member 84 inplace. Guide 84 includes a cylindrical center portion or guide tube 88defining a slide surface for coupling 71 as the latter is reciprocatedin response to movement of throttle lever 76, and to fiexure ofdiaphragm 52. Cylindrical portion 88 of said guide member 84 locates compression spring 79 along its outer surface. A seal ring 100 is retainedin the groove in the periphery of member 71 and slidably contacts wallsof the guide member center portion 88 to form a sliding fluid tightseal.

To achieve the necessary limited free movement between metering rod 66and coupling 71, the latter is provided with an axial bore 70 having adiameter approximating, yet smaller than the diameter of projection 61.To permit ease of assembly of members 61 to 71, and also to facilitatereplacement of metering rod 66 as needed, coupling 71 locking end is soformed to define a spring type locking socket 65. As presently shown,particularly in FIGURES 3 and 8, socket 65 wall is weakened by one ormore longitudinal slots 19 and 23 to define a plurality of segments 89therebetween. An inturned lip 92 or similar protuberance extendingradially inwardly from each segment 89, forms a limiting means againstwhich surface 64 may abut, thereby limiting longitudinal movement ofmetering rod 66.

For assembling coupling 71 to metering rod head 53, segments 89 may besprung apart when coupling 71 is removed from the close fitting walls ofcylindrical portion 88. In such position, shoulder 73 of coupling 71will come to rest on the upper surface of retainer 84. Longitudinalslots 19 and 23 formed in the lower half of coupling 71 will then extenddownwardly beneath the lower rim of cylindrical portion 88 thuspermitting the respective segments 89 to be forced apart sufiiciently toopen bore 70 and permit entry of the head projection 61. Segments 89 arethen returned to their closed position with the inturned lip 92overlying projection 61 so that metering rod 66 is in effect movably andslidably retained within the coupling 71. The coupling and metering rodare then drawn together up into the guide portion 88 of guide member 84.

Referring to FIGURE 4, plenum chamber defined by the respectivediaphragm 52 and guide member 84 is connected to a source of vacuum atthe engine intake manifold M. This is achieved by a passage 92 formed ina wall of mixing conduit 12 at a position below the carburetor throttlevalve 22. Passage 92' is communicated through an elongated passage 95 toa cross boring 94 which terminates in the plenum chamber 95. Plenum 95may also be communicated to intake manifold M at any of severallocations other than in the carburetor itself.

Referring to FIGURES 3, 5, 6, and 7, the relative position of thecoupling member 71 and metering rod 66 are shown during various phasesof engine operation. In FIG- URE 3, the engine is illustrated at restwith no appreciable vacuum being drawn in the intake manifold M andconsequently no vacuum being drawn on plenum 95. Thus, with throttle 22in the closed position, coupling 71 will be withdrawn upwardly to amaximum position by throttle lever 76 which is connected to the throttleactuating means. Seating surface 64 of projection 61 will thus besupported on the upper edge of lip 92 thereby lifting metering pin 66 toposition the widest part 45 of end 68 in nozzle opening 69. Diaphragm 52is in a partially withdrawn position since there is no vacuum conditionwithin plenum 95 and since compression spring 89 is of sufiicientstrength to overcome the upward pull of the throttle lever 76, whichspring would otherwise urge the diaphragm toward the downward position.

At cranking or start up of the engine, a maximum vacuum of about .19inch of water is drawn at intake manifold M thereby immediatelyevacuating plenum 95 while maintaining the position of the coupling 71substantially as shown in FIGURE 3. This pre-supposes that the engine isstarted in the normal manner with the throttle I substantially closed orcracked. Thus, diaphragm 52 will be drawn into plenum 95 and therebybringing the inner surface of cup 78 into engagement with the lowersurface of the guide portion 88. In thisposition diaphragm 52 iswithdrawn to its maximum upward position and metering rod 66 is sodisposed as to permit the lower end 68 to locate the portion 45 for theproper engine idle position.

With the engine running at open throttle, as shown in FIGURE 6, coupling71 is depressed partially into guide portion 88 by the throttle lever76. The upper seating surface 63 of projection 61 will be in abuttingengagement with the end wall of the socket 65 formed in the lower partof the coupling 71 thereby urging the metering rod 66 downwardly therebypositioning a narrower portion 55 of the rod in metering orifice 69. Atpart throttle, the manifold vacuum will substantially drop off therebylessening the vacuum created in the plenum 95. With the decrease invacuum, diaphragm 52 will be unable to resist the position urging of thecoupling 61 by lever 76 to force the metering rod 66 into its normalrunning position.

FIGURE 7 illustrates the position of the throttle lever 76 and coupling71 with the metering rod depressed to its maximum position. Thus,shoulder 97 will abut the hub 98 thereby precluding further downwardmovement of the metering rod 66. Any further depression of the throttlelever 76 will result not in the movement of the coupling 71 to furtherdisplace the metering rod 66, but rather in spring 77 being furtherdepressed until the throttle lever 76 has reached its point of maximumdepression.

Illustrative of the preferred operation of the invention, againreferring to FIGURES 3 and 5, at engine start-up a maximum vacuum willbe created in inlet manifold M, which is communicated to plenum 95.There is thus a tendency to withdraw metering rod 66 upwardly throughorifice 69 in response to movement of the diaphragm 52. However,engagement of the projection 61 against lip 92 of coupling 71 willlocate metering rod 66 in accordance with a desired predeterminedposition by abutment of the cup against the lower edge of guide portion88.

During engine idle, the throttle will gradually be cracked to increasethe speed of the engine. As this happens, the vacuum in plenum 95decreases substantially thereby permitting diaphragm 52 to be urged byspring 79 from the plenum.

This idle position is such that the annulus opening defined by meteringrod end 68 and orifice 69, affords an optimum rate of fuel flow tomaintain the engine at idle speed.

Thereafter, as manifold vacuum decreases, spring 79 will overcome inpart the decreased vacuum in plenum 95 and urge diaphragm 52 downwardlythereby lowering metering rod 66 to define a larger opening at orifice69 and allow a greater fuel flow. As the engine is subjected to agreater load, the resulting decrease in manifold vacuum will permit rod66 to adjust itself automatically downwardly and provide a richer airfuel mixture without a comparable adjustment in the throttle or throttleactuating means.

This automatic adjustment in rod 66 is limited by freedom of movement ofprojection 61 in socket 65 which allows diaphragm 52 entire controlregarding the positioning of projection 61.

It is clear from the foregoing that the carburetor presently describedaffords several advantages heretofore unrealized in the art. For onething, a more accurate metering of fuel to the discharge nozzle assuresa more economical utilization of the fuel energy. Further, and by nomeans secondarily in importance, is the minimization or completeelimination of undesirable emission which 6 would tend to aggravate asmog problem. Also, the novel arrangement permits automatic adjustmentof the carburetor air fuel mixture calibration in immediate response toa particular engine demand or requirement such as a minor load imposedon the engine.

In the latter instance, the metering rod is normally adjusted byactuation of the throttle. However, when the engine encounters a roadcondition which would tend to impose an added load, the instantaneousdecrease in intake manifold pressure is transmitted to the air motorthereby causing the latter to override control by the throttle andpermit the metering rod to freely adjust and cause a richer air-fuelmixture to be delivered to the engine. The richer mixture will of courseprevail until such time as the engine power adjusts to the road load,thereby automatically initiating a change in intake manifold vacuum,which in turn repositions the metering rod to its original location tobe controlled by the throttle.

It is appreciated that the foregoing description is designed forapplication to a variety of carburetor structures. It is therefore seenthat the unique arrangement can be modified and changed withoutdeparting from the spirit and scope of the invention.

We claim:

1. In a carburetor for an internal combustion engine including a body, amixture conduit formed in the body, a throttle valve having a shaftjournalled in the mixture conduit and being operable to regulate passageof air fuel mixture therethrough, an actuating mechanism connected tosaid throttle, a fuel bowl formed in said body holding a supply of fuel,a ventiuri in said body including a nozzle, a fuel duct carrying a fuelstream from said fuel bowl to said nozzle for injection into saidmixture conduit, a metering orifice in said fuel duct adapted toregulate said fuel stream, an air motor associated with said carburetorand connected to a source of varying vacuum in said engine, said airmotor having a displaceable diaphragm at one wall thereof, and beingmoveable between inner and outer positions in response to variations insaid vacuum source, a metering rod having opposed ends including atapered end disposed in said metering orifice and having the other endengaging said diaphragm to be reciprocably moved between said inner andouter positions in said orifice in response to a pressure change in saidair motor, a lost motion connection operably engaging said throttleactuating mechanism with said metering rod and includ- 111g;

(1) an elongated coupling member (71) extending coaxially of saidmetering rod and engaging said throttle actuating mechanism,

(a) a cavity formed in the end of said elongated coupling member andextending coaxially thereof,

(b) said metering rod including a projection at the end thereof oppositeto said metering end, said cavity includes an opening defined by aninwardly projecting lip (92) supporting said metering rod, the wall ofsaid cavity being slotted to provide segments and permit lateraldisplacement thereof whereby said opening will 1 be sufiicientlyenlarged to receive said projection thereby loosely retaining the latterin said cavity when said segments are returned to an undisplacedposition, said projection being loosely received in said cavity topermit limited movement of said rod with respect to said couplingmember,

whereby said metering rod is adjustable for regulating the positionthereof with respect to said orifice in immediate response to variationsin the degree of vacuum in said engine, independent of the throttleposition.

2. In a carburetor as defined in claim 1 including a guide membercarried in said air motor and spaced from said diaphragm to define aplenum chamber, said guide member including a guide tube extendingco-axial of said metering rod, and said coupling being slidably receivedin said guide tube.

3. In a carburetor as defined in claim 2 including resilient seal ring(100) forming a sliding fluid tight seal between said guide tube andsaid coupling member.

4. In a carburetor as defined in claim 1, wherein said projection (61)on said metering rod includes;

(a) a slide surface (67) registered in said opening, and an enlargedportion having a diameter greater than said opening to permit retentionof said projection in said cavity.

References Cited UNITED STATES PATENTS Kemp 26l-69 Baker 26151 Jones26151 X Moseley.

Moseley et a1. 261-51 Carlson et a1. 261-69 X Read 26151 Powell et a126169 X Kalert et a1. 261-69 Newman et al. 26169 15 RONALD R. WEAVER,Primary Examiner.

1. IN A CARBURETOR FOR AN INTERNAL COMBUSTION ENGINE INCLUDING A BODY, AMIXTURE CONDUIT FORMED IN THE BODY, A THROTTLE VAVLE HAVING A SHAFTJOURNALLED IN THE MIXTURE CONDUIT AND BEING OPERABLE TO REGULATE PASSAGEOF AIR FUEL MIXTURE THERETHROUGH, AN ACTUATING MECHANISM CONNECTED TOSAID THROTTLE, A FUEL BOWL FORMED IN SAID BODY HOLDING A SUPPLY OF FUEL,A VENTURI IN SAID BODY INCLUDING A NOZZLE, A FUEL DUCT CARRYING A FUELSTREAM FROM SAID FUEL BOWL TO SAID NOZZLE FOR INJECTION INTO SAIDMIXTURE CONDUIT, A METERING ORIFICE IN SAID FUEL DUCT ADAPTED TOREGULATE SAID FUEL STREAM, AN AIR MOTOR ASSOCIATED WITH SAID CARBURETORAND CONNECTED TO A SOURCE OF VARYING VACUUM IN SAID ENGAINE, SAID AIRMOTOR HAVING A DISPLACEABLE DIAPHRAGM AT ONE WALL THEREOF, AND BEINGMOVEABLE BETWEEN INNER AND OUTER POSITIONS IN RESPONSE TO VARIATIONS INSAID VACUUM SOURCE, A METERING ROD HAVING OPPOSED ENDS INCLUDING ATAPERED END DISPOSED IN SAID METERING ORIFICE AND HAVING THE OTHER ENDENGAGING SAID DIAPHRAGM TO BE RECIPROCABLY MOVED BETWEEN SAID INNER ANDOUTER POSITIONS IN SAID ORIFICE IN RESPONSE TO A PRESSURE CHANGE IN SAIDAIR MOTOR, A LOST MOTION CONNECTION OPERABLY ENGAGING SAID THROTTLEACTUATING MECHANISM WITH SAID METERING ROD AND INCLUDING; (1) ANELONGATED COUPLING MEMBER (71) EXTENDING COAXIALLY OF SAID METERING RODAND ENGAGING SAID THROTTLE ACTUATING MECHANISM, (A) A CAVITY FORMED INTHE END OF SAID ELONGATED COUPLING MEMBER AND EXTENDING COAXIALLYTHEREOF, (B) SAID METERING ROD INCLUDING A PROJECTION AT THE END THEREOFOPPOSITE TO SAID METERING END, SAID CAVITY INCLUDES AN OPENING DEFINEDBY AN INWARDLY PROJECTING LIP (92) SUPPORTING SAID METERING ROD, THEWALL OF SAID CAVITY BEING SLOTTED TO PROVIDE SEGMENTS AND PERMIT LATERALDISPLACEMENT THEREOF WHEREBY SAID OPENING WILL BE SUFFICIENTLY ENLARGEDTO RECEIVE SAID PROJECTION THEREBY LOOSELY RETAINING THE LATTER IN SAIDCAVITY WHEN SAID SEGMENTS ARE RETURNED TO AN UNDISPLACED POSITION, SAIDPROJECTION BEING LOOSELY RECEIVED IN SAID CAVITY TO PERMIT LIMITEDMOVEMENT OF SAID ROD WITH RESPECT TO SAID COUPLING MEMBER, WHEREBY SAIDMETERING ROD IS ADJUSTABLE FOR REGUALTING THE POSITION THEREOF WITHRESPECT TO SAID ORIFICE IN IMMEDIATE RESPONSE TO VARIATIONS IN THEDEGREE OF VACUUM IN SAID ENGINE, INDEPENDENT OF THE THROTTLE POSITION.